A cutting tool of the type initially mentioned is previously known by U.S. Pat. No. 4,024,777. More precisely, this document describes and exemplifies a turning tool of the type that, in addition to a holder or bar, includes an indexable cutting insert having a parallelepipedic shape, which has four alternately individually usable cutting edges, and which can be rotationally secured in a seat with two side support surfaces perpendicular to each other. This cutting insert may be detachably mounted in an attachment on a front part of a shaft included in a device, and which turns in connection with the same being rectilinearly thrust outward to a position in which the cutting insert has left the seat. In a rear part, the shaft includes a piston, which is sealed against the inside of a cylindrical boring, in which the piston is movable back and forth. In other words, the boring forms a pressure fluid cylinder, which is divided into a plus chamber and a minus chamber to and from which a pressure fluid (e.g., liquid or gas) can be supplied and evacuated, respectively, for either thrusting out the cutting insert and indexing the same, or bringing the same back to the operative position in the seat. Turning of the shaft is provided for by a fixed guide pin, which projects into the boring and the piston and engages the gaps between a number of front teeth having obliquely cut end edge surfaces, with which obliquely cut edge surfaces of a rear set of teeth included in the same piston interact.
A disadvantage of this known tool is that the clamping of the cutting insert in the appurtenant seat is unreliable and it is a problem to accommodate tolerances for the fitting of the cutting insert into the seat. Another disadvantage is that the tool is complex and expensive to manufacture.